I. Substrate metabolism and interrelationships in the ovine fetus in utero. II. Measurement of carbon dioxide production and substrate oxidation by the ovine fetus in utero using 14C-labelled compounds
Kitts, D.D.; Krishnamurti, C.R.
Canadian Journal of Animal Science 62(2): 397-415
1982
ISSN/ISBN: 0008-3984 Document Number: 515536
The trace technique was used to study substrate metabolism and re-entry of the tracer to the ovine fetal circulation. Ewes with synchronized oestrous cycles were used. At 120-130 days gestation, external saphenous veins of the fetuses were catheterized and jugular catheters were fitted to the ewes. 50 mu Ci of radioactive substrate was injected as an i/v bolus; the substrates used were glucose, lactate and alanine, injected singly or as mixtures. From the results of monitoring fetal and maternal blood, and examination of fetal weights, it appeared that: because blood glucose and lactate levels remained constant, experimental conditions had preserved a satisfactory steady state; fetal body weight is directly related to umbilical glucose uptake; lactate is recycled to a greater extent than glucose; and more work is needed to investigate gluconeogenic precursors in the sheep fetus. Part II reported oxidation rates of 31% for glucose, 36% for lactate, 27% for alanine and 16% for acetate. 15% of carbon dioxide was derived from glucose oxidation and 14% from lactate, but only 40% of total carbon dioxide production was accounted for by substrate oxidation.